In various industrial sectors, for example the manufacture of iron and steel, sugar, cement, foodstuffs, etc. the manufacturing processes require a shaft, tubes or tanks with large dimensions and which are often subject to external mechanical, thermal or vibrational loads to be driven in rotation and immobilized in particular positions.
They are usually driven via a gear ring or wheel of large diameter mounted on the element to be driven.
In some applications, the operating cycle requires energetic immobilization in a stopped position of the receiving machine, which is subject to various loads.
This is the case, for example, when injecting gaseous fluids into a converter or any other similar tank during the production of steel or any other product, with the consequent presence of high vibrational stresses on the kinematic system. The injection of gaseous fluids under pressure into converter ladles generates vibrational stresses and high stresses likely to lead to fatigue damage of the gear transmission units and this makes it essential to oversize certain elements of the transmission units by a safety factor greater than two or even three.
These stresses occur either continuously, with varying intensity, or with violent intensities during the blowing of gases at periods of a few minutes.
In new converter designs, the center of gravity of the ladle is at a greater or lesser distance from its pivot axis. The proximity of the center of gravity to the axis occasions very high vibrational intensities and causes dynamic instability of the converter.
The element of the kinematic system, i.e. the toothed ring in the case of a converter, must be immobilized with total safety in a precise angular position and without any backlash.
Devices for immobilizing an element by eliminating the backlash of gears in the kinematic system of a reduction gear by contact with the opposite flanks of the same mobile member are well known in the art.
In this case, the reduction gears comprise a ring connected to the element to be immobilized and driven by two gears. A tilting primary reduction gear is mounted on each gear, the forces being balanced by a compression or tension bar connecting the two primary reduction gears.
Contact without clearance is obtained by means of a hydraulic ram which tilts the two primary reduction gears in opposite directions to prestress the opposite flanks of the teeth.
Another device well known in the art for immobilizing an element, consisting of a gear ring, for example, by means of a split torque reduction gear is made up of two autonomous casings each carrying a gear driving the gear ring.
The tangential forces are balanced between the two casings by means of a torsion bar. The contact between the opposite flanks and the immobilizing of the ring are obtained by the forced displacement of the two casings in the same direction, generally the downward direction, to effect the required prestressing.
This movement is obtained with one or two hydraulic rams which swing the torsion bar.
In the case of a single ram, the device is positioned directly on the torsion bar, and in the case of two rams the device applies the force directly to each of the two casings.